The Research of Moonpool Size Effect on the Hydrodynamic Performance of FDPSO

2011 ◽  
Author(s):  
Yuefeng Wei ◽  
Jianmin Yang ◽  
Gang Chen ◽  
Zhiqiang Hu
Keyword(s):  
Numerical Analysis ◽  
Size Effect ◽  
White Noise ◽  
Natural Frequency ◽  
Model Test ◽  
Hydrodynamic Performance ◽  
Ocean Engineering ◽  
Floating Platform ◽  
Paper Making ◽  
Reliable Model

FDPSO is a multifunction floating platform, which has the combined function of drilling, production, storage and offloading oil. The moonpool is necessary for drilling operation and the moonpool size effect will play a role on the hydrodynamic performance of FDPSO. A study of the moonpool size effect on such performance of FDPSO hull is presented in this paper, making use of numerical analysis and model tests techniques. The code WADAM is used for the hydrodynamic performance analysis. A model test aiming to validate the accuracy of the numerical analysis results was conducted in the Ocean Engineering basin in the State Key Laboratory of Ocean Engineering in the Shanghai Jiao Tong University. The model test included decaying test and white noise test. The decaying tests are performed in still water for heave, roll and pitch. White noise tests were carried out to obtain the RAO of FDPSO, with the wave incoming direction of 180° and 135°. The numerical results show a good agreement with the model test results, indicating a reliable model. The “piston” motion of the water inside the moonpool is significant, affecting the hydrodynamic performance of the FDPSO. The effect of moonpool size on the hydrodynamic performance of the FDPSO is analyzed through a numerical method. The relationship between the piston natural frequency of the water column inside the moonpool and its diameter and draft, are studied. An empirical formula of the “piston” natural frequency is proposed, and its validity is assessed.

Numerical and Model Test Investigation on the Motion Characteristic of FDPSO and the Sheltered Riser Vessel

2010 ◽  
Author(s):  
Yuefeng Wei ◽  
Zhiqiang Hu ◽  
Gang Chen ◽  
Jianmin Yang
Keyword(s):  
West Africa ◽  
Model Test ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Shielding Effect ◽  
Ocean Engineering ◽  
Floating Platform ◽  
Test Investigation ◽  
Moon Pool

FDPSO is a multifunction floating platform, capable of drilling, production, storage and offloading. Sheltered Riser Vessel (SRV) serves as an independent buoyant hull to provide riser tensions, which is situated in the moon pool of FDPSO. Due to the shielding effect of moon pool, the motion of SRV is very small, so as to meet the requirement of drilling. In order to validate the basic FDPSO and SRV concepts, a model test was conducted in the basin of Ocean Engineering in the State Key Lab of Ocean Engineering in Shanghai Jiao Tong University. The storm tests were carried out in wave extremes of West Africa and white noise wave environments. Potential theory was adopted to calculate the motion performance of FDPSO system. Frequency domain analysis of the motion response amplitude operator (RAO) and time domain analysis in the extreme sea condition are both conducted. The comparison between the numerical simulation and model test results shows that the results of RAO and statistical value of response time series in the extreme sea condition are coincident. It is indicate that the method is credible and the concepts of FDPSO and SRV are likely to be feasible in West Africa.

Installation of a Submerged Buoy for Supporting Risers (BSR) System in Campos Basin Site

2011 ◽  
Author(s):  
Jairo Bastos de Arau´jo ◽  
Jose´ Carlos Lima de Almeida ◽  
Antonio Carlos Fernandes
Keyword(s):  
Numerical Analysis ◽  
Model Test ◽  
Water Depth ◽  
Water Model ◽  
Floating Platform ◽  
Mooring Lines ◽  
Sea Bottom ◽  
Campos Basin ◽  
Steel Catenary Risers ◽  
Field Location

The BSR (Buoy for Supporting Risers) concept is composed by a submerged buoy anchored to the sea bottom by tethers and intended to support risers coming from the bottom (probably SCRs — Steel Catenary Risers) and going to the floating platform (probably with flexible jumpers). For the case under analysis here, the main dimensions of the BSR prototype are 27.2 m length × 27.2 m width × 5.0 m depth. The paper describes all final full scale installation step so that the BSR may be considered a suitable technology. The installation indeed was the great challenge of this design due the size of the hull. The present work also evaluates numerically and experimentally a specific new manner to install the BSR with the support of auxiliary mooring lines among with the four tethers connected to it. One of the installation premises was to make use of Anchor Handling Supply Vessels instead of Crane Vessels. After this numerical analysis, the work went on by performing model tests that simulates the operation in a deep water model basin using 1:40 scale. The model test anticipated several problems such as the chain stopper weakness in the operation and others as discussed in this paper. As a conclusion the work was devised the most important parameters during the system installation and suggested ways to improve the methodology. In November 2009 the BSR was installed in 500 m of water depth at Congro field location, Campos Basin, offshore Brazil. The tethers were adjusted in January 2010 and in March 2010 two risers were installed. Thenceforward the last edge of this knowledge was considered over passed.

1:52 Scale Testing of the First US Commercial Scale Floating Wind Turbine, VolturnUS: Testing Overview and the Evolution of Scale Model Testing Methods

2017 ◽  
Author(s):  
Matthew J. Fowler ◽  
Andrew J. Goupee ◽  
Christopher Allen ◽  
Anthony Viselli ◽  
Habib Dagher
Keyword(s):  
Model Test ◽  
Wind Wave ◽  
Model Testing ◽  
Model Tests ◽  
Scale Model ◽  
Test Facility ◽  
Ocean Engineering ◽  
Floating Platform ◽  
Design Validation ◽  
Floating Offshore Wind Turbines

Over the past 6 years, the University of Maine (UMaine) has been an active contributor in research and scale-model testing of floating offshore wind turbines (FOWTs). This paper serves to share the evolution of UMaine’s scale-model testing pedigree by exploring the various test campaigns at a high level, culminating with the design validation of the VolturnUS floating platform. These model test campaigns have each provided key insights into the behavior of FOWT platforms as well as improving the ability to perform model tests of FOWTs. In 2011, the UMaine-led DeepCwind Consortium carried out 1/50-scale model tests of a generic tension leg platform (TLP), a semi-submersible (semi), and a spar-buoy (spar) floating platform at the Maritime Research Institute Netherlands (MARIN) test facility. The designs were Froude-scaled and supported a scaled version of the 5-MW National Renewable Energy Laboratory (NREL) offshore research turbine. Data from these tests has been used extensively for numerical simulation validation efforts using NREL’s computer-aided engineering software FAST and laid the foundation for UMaine’s design efforts on VolturnUS. In 2013, UMaine conducted another test campaign at MARIN using the original semi-submersible from 2011 with an improved turbine as well as a 1:50-scale model of the VolturnUS concrete semi-submersible design. The improved DeepCwind semi-submersible data is currently being utilized in the validation of a large number of other analysis codes as part of the International Energy Agency’s OC5 project. In 2015, UMaine opened its own Wind/Wave test facility, the Alfond Wind/Wave Ocean Engineering Laboratory (W2). Utilizing this new facility, UMaine tested the 1:50-scale model DeepCwind semi-submersible, repeating the tests from MARIN, to validate the experimental equipment and procedures as well as demonstrate the capability of the W2. In 2016 UMaine carried out testing of a 1:52-scale model of the 100% design of the VolturnUS with a 6-MW topside as a final design validation to support the US Department of Energy-supported, full-scale Aqua Ventus demonstration project scheduled to be connected to the grid in 2019. A newly designed 6-MW scale model turbine was used in this test and the performance-matched turbine design methodology is described. Selected results from the test campaign and preliminary numerical comparisons are discussed as well as key lessons learned from the model test campaigns are presented.

Identifying VIV Vibration Modes by Use of the Empirical Orthogonal Functions Technique

2002 ◽  
Author(s):  
Gudmund Kleiven
Keyword(s):  
Model Test ◽  
Vibration Mode ◽  
Multivariate Data ◽  
Empirical Orthogonal Functions ◽  
Mode Shapes ◽  
Data Sets ◽  
Vibration Modes ◽  
Ocean Engineering ◽  
Orthogonal Functions ◽  
Related Technique

The Empirical Orthogonal Functions (EOF) technique has widely being used by oceanographers and meteorologists, while the Singular Value Decomposition (SVD being a related technique is frequently used in the statistics community. Another related technique called Principal Component Analysis (PCA) is observed being used for instance in pattern recognition. The predominant applications of these techniques are data compression of multivariate data sets which also facilitates subsequent statistical analysis of such data sets. Within Ocean Engineering the EOF technique is not yet widely in use, although there are several areas where multivariate data sets occur and where the EOF technique could represent a supplementary analysis technique. Examples are oceanographic data, in particular current data. Furthermore data sets of model- or full-scale data of loads and responses of slender bodies, such as pipelines and risers are relevant examples. One attractive property of the EOF technique is that it does not require any a priori information on the physical system by which the data is generated. In the present paper a description of the EOF technique is given. Thereafter an example on use of the EOF technique is presented. The example is analysis of response data from a model test of a pipeline in a long free span exposed to current. The model test program was carried out in order to identify the occurrence of multi-mode vibrations and vibration mode amplitudes. In the present example the EOF technique demonstrates the capability of identifying predominant vibration modes of inline as well as cross-flow vibrations. Vibration mode shapes together with mode amplitudes and frequencies are also estimated. Although the present example is not sufficient for concluding on the applicability of the EOF technique on a general basis, the results of the present example demonstrate some of the potential of the technique.

Full Scale Fairing Qualification Tests

2015 ◽  
Author(s):  
Yiannis Constantinides ◽  
Stergios Liapis ◽  
Don Spencer ◽  
Mohammed Islam ◽  
Kjetil Skaugset ◽  
...  
Keyword(s):  
Fatigue Failure ◽  
Model Test ◽  
Hydrodynamic Performance ◽  
Documented Case ◽  
Vortex Induced Vibrations ◽  
Viv Suppression ◽  
Single Pipe ◽  
Interference Tests ◽  
Fin Design ◽  
Novel Design

Production risers as well as drilling risers are often subjected to Vortex-induced vibrations (VIV) when exposed to ocean currents. VIV have been observed in the field and can cause fatigue failure and excessive drag on the riser. In order to suppress VIV and reduce drag, fairings are often used. This paper presents hydrodynamic qualification tests for two types of fairings: the short crab claw (SCC) and a tapered dual fin design. The short crab claw fairing design is a novel design that was developed by the Norwegian Deepwater Programme (NDP). As will be detailed in this paper, the SCC design offers very low drag, completely suppresses VIV and reduces riser interference. In 2012, a model test campaign was undertaken to understand and qualify the hydrodynamic performance of fairings at prototype conditions. The program consisted of testing the three fairing geometries and a strake to understand the stand-alone performance in VIV and the performance in interference. This was accomplished by utilizing a single pipe setup for the standalone test and a two-pipe setup for the interference tests. The paper reports the results of the program and draws conclusions on the hydrodynamic performance of the VIV suppression devices tested. Overall, all VIV suppression devices tested were able to suppress VIV with the SCC fairing being the most effective. In all cases tested, the downstream fairings / strakes were very effective in suppressing VIV in an interference scenario where a fairing was placed upstream. Contrary to the well-documented case of two strakes in tandem, in this case the upstream fairings did not reduce the effectiveness of the downstream fairings/strakes.

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